Bottom Line:
The rudimental Zn(OH)(2) core is eliminated with ammonia solution.In addition, ZnO-based heterostructures possessing better chemical or physical properties can also be prepared via this unique templating process.Room-temperature photoluminescence spectra of the heterostructures and hollow structures are also shown to study their optical properties.

ABSTRACTA size-controlled Zn(OH)(2) template is used as a case study to explain the chemical strategy that can be executed to chemically engineering various nanoscale cavities. Zn(OH)(2) octahedron with 8 vertices and 14 edges is fabricated via a low temperature solution route. The size can be tuned from 1 to 30 μm by changing the reaction conditions. Two methods can be selected for the hollow process without loss of the original shape of Zn(OH)(2) template. Ion-replacement reaction is suitable for fabrication of hollow sulfides based on the solubility difference between Zn(OH)(2) and products. Controlled chemical deposition is utilized to coat an oxide layer on the surface of Zn(OH)(2) template. The abundant hydroxyl groups on Zn(OH)(2) afford strong coordination ability with cations and help to the coating of a shell layer. The rudimental Zn(OH)(2) core is eliminated with ammonia solution. In addition, ZnO-based heterostructures possessing better chemical or physical properties can also be prepared via this unique templating process. Room-temperature photoluminescence spectra of the heterostructures and hollow structures are also shown to study their optical properties.

Mentions:
Figure 2a shows a SEM image of the Zn(OH)2 template synthesized by decomposing the Zn(OH)42− precursor directly in a low temperature aqueous solution (50 °C). The diameter of the octahedra is uniform and at 3–4 μm. The magnified image (Fig. 2b) reveals that the as-prepared particle has unique octahedral shape with 8 vertices and 14 edges. The crystals are well defined with smooth surface, which can be confirmed by the corresponding TEM image shown in Fig. 2c. The XRD patterns in Fig. 2d show that all of the diffraction peaks of the template can be perfectly indexed to orthorhombic Zn(OH)2 (JCPDS Card No. 74-0094). While the diffraction peaks of the annealed sample match well with hexagonal wurtzite ZnO (JCPDS Card No. 79-0205). The TG and DSC curves, displayed in Fig. 3a, suggest that this template remains stable before 100 °C and experiences a steep weigh loss around 135 °C. The weight loss ratio is about 17.5% which accords with theory calculation (18.3%), indicating the probable formula for this template is Zn(OH)2. From the FT-IR spectrum of the template (Fig. 3b), the strong absorption around 3,400 cm−1 corresponds to the O–H stretching from the hydroxyl groups located on the surface of Zn(OH)2 particles. These hydroxyl groups exhibit good combining ability toward the positive charged metal cations, which can lead to the enrichment of the metal cations on the surface of the template. Figure 3b also represents the comparative FT-IR spectrum of the ZnO sample after calcination. The peak around 3,400 cm−1 is substantially abated. Though many researches have been done to tailor the shape and size of the materials to enrich their properties, controllable fabrication still remains a big challenge in material science. The average diameter of Zn(OH)2 octahedra can be readily tuned in a large range by altering the reaction parameters. All of the as-prepared Zn(OH)2 octahedra are uniform and the diameters are approximately at 25–30, 5–7, and 1–2 μm, respectively (Fig. 4). To our knowledge, this is the first time to study the size control over Zn(OH)2 crystal and fabricate hollow structures by using Zn(OH)2 octahedron as sacrificing template. By using these templates, a series of hollow structured materials with controllable sizes can be fabricated.

Mentions:
Figure 2a shows a SEM image of the Zn(OH)2 template synthesized by decomposing the Zn(OH)42− precursor directly in a low temperature aqueous solution (50 °C). The diameter of the octahedra is uniform and at 3–4 μm. The magnified image (Fig. 2b) reveals that the as-prepared particle has unique octahedral shape with 8 vertices and 14 edges. The crystals are well defined with smooth surface, which can be confirmed by the corresponding TEM image shown in Fig. 2c. The XRD patterns in Fig. 2d show that all of the diffraction peaks of the template can be perfectly indexed to orthorhombic Zn(OH)2 (JCPDS Card No. 74-0094). While the diffraction peaks of the annealed sample match well with hexagonal wurtzite ZnO (JCPDS Card No. 79-0205). The TG and DSC curves, displayed in Fig. 3a, suggest that this template remains stable before 100 °C and experiences a steep weigh loss around 135 °C. The weight loss ratio is about 17.5% which accords with theory calculation (18.3%), indicating the probable formula for this template is Zn(OH)2. From the FT-IR spectrum of the template (Fig. 3b), the strong absorption around 3,400 cm−1 corresponds to the O–H stretching from the hydroxyl groups located on the surface of Zn(OH)2 particles. These hydroxyl groups exhibit good combining ability toward the positive charged metal cations, which can lead to the enrichment of the metal cations on the surface of the template. Figure 3b also represents the comparative FT-IR spectrum of the ZnO sample after calcination. The peak around 3,400 cm−1 is substantially abated. Though many researches have been done to tailor the shape and size of the materials to enrich their properties, controllable fabrication still remains a big challenge in material science. The average diameter of Zn(OH)2 octahedra can be readily tuned in a large range by altering the reaction parameters. All of the as-prepared Zn(OH)2 octahedra are uniform and the diameters are approximately at 25–30, 5–7, and 1–2 μm, respectively (Fig. 4). To our knowledge, this is the first time to study the size control over Zn(OH)2 crystal and fabricate hollow structures by using Zn(OH)2 octahedron as sacrificing template. By using these templates, a series of hollow structured materials with controllable sizes can be fabricated.

Bottom Line:
The rudimental Zn(OH)(2) core is eliminated with ammonia solution.In addition, ZnO-based heterostructures possessing better chemical or physical properties can also be prepared via this unique templating process.Room-temperature photoluminescence spectra of the heterostructures and hollow structures are also shown to study their optical properties.

ABSTRACTA size-controlled Zn(OH)(2) template is used as a case study to explain the chemical strategy that can be executed to chemically engineering various nanoscale cavities. Zn(OH)(2) octahedron with 8 vertices and 14 edges is fabricated via a low temperature solution route. The size can be tuned from 1 to 30 μm by changing the reaction conditions. Two methods can be selected for the hollow process without loss of the original shape of Zn(OH)(2) template. Ion-replacement reaction is suitable for fabrication of hollow sulfides based on the solubility difference between Zn(OH)(2) and products. Controlled chemical deposition is utilized to coat an oxide layer on the surface of Zn(OH)(2) template. The abundant hydroxyl groups on Zn(OH)(2) afford strong coordination ability with cations and help to the coating of a shell layer. The rudimental Zn(OH)(2) core is eliminated with ammonia solution. In addition, ZnO-based heterostructures possessing better chemical or physical properties can also be prepared via this unique templating process. Room-temperature photoluminescence spectra of the heterostructures and hollow structures are also shown to study their optical properties.